Single radar / Florida

Tallahassee radar KTLH

The weather service radar at Tallahassee, Florida, alone: each picture it makes from its own scans, at four tilts from its lowest up, every few minutes. Reflectivity, velocity, storm relative velocity, correlation coefficient and differential reflectivity, the storms it tracks and where they are headed, and how high its beam passes. How to read them.

Latest scan: 6:30 AM UTC
Scanning: Precipitation mode, pattern 212
Tilts: 0.5°, 1.3°, 2.4°, 3.1°
Stands at: 30.397°N 84.329°W, 63 ft above sea level
Reaches: 286 mi with reflectivity, 186 mi with velocity, 143 mi with storm relative velocity

KTLH on the map

Storms it tracks

The radar follows each storm cell from scan to scan, measures the way it is moving, and puts it ahead 15 to 60 minutes. Each is drawn on the map above, its track to the hour ahead marked each quarter hour.

Storm cells KTLH tracks, from its scan of 6:22 AM UTC
Storm	Where	Moving	In 30 minutes	In 60 minutes	Last forecast off by
J3	120 mi southeast of the radar120 mi from the radar, bearing 144°	Toward the northeast at 43 mph	115 mi southeast of the radar	7 mi west northwest of Bronson, FL	0.2 mi
A7	2 mi west southwest of Tarpon Springs, FL182 mi from the radar, bearing 149°	Toward the north northeast at 33 mph	2 mi north northeast of Hudson, FL	-	1.2 mi
E5	At Chiefland, FL108 mi from the radar, bearing 126°	Toward the northeast at 26 mph	6 mi east of Trenton, FL	6 mi south of High Springs, FL	0.1 mi
C3	11 mi northeast of Watertown, FL112 mi from the radar, bearing 94°	Toward the north northeast at 58 mph	124 mi east of the radar	-	1.8 mi
D7	101 mi east of the radar101 mi from the radar, bearing 84°	Toward the north northeast at 35 mph	110 mi east northeast of the radar	121 mi east northeast of the radar	0.8 mi
I0	116 mi southeast of the radar116 mi from the radar, bearing 139°	Toward the northeast at 33 mph	-	-	4.3 mi
Y2	105 mi east northeast of the radar105 mi from the radar, bearing 76°	Toward the north northeast at 43 mph	14 mi south southwest of Waycross, GA	-	1.3 mi
K4	9 mi north northwest of Five Points, FL97 mi from the radar, bearing 92°	First seen this scan	-	-	0 mi

How high it sees

The beam leaves the radar tilted up and the earth curves away under it, so the farther from the radar, the higher it passes. Rain or snow falling under the lowest beam is not seen: far from the radar, shallow snow and drizzle can fall unseen. The heights are the standard ones, the air bending the beam as the weather service’s own rule takes it.

The middle of each tilt’s beam, in feet above the radar’s antenna, and how wide the beam has grown
Tilt	25 mi	50 mi	100 mi	150 mi	200 mi
0.5°	1,500 ft	3,600 ft	9,600 ft	18,200 ft	29,200 ft
1.3°	3,300 ft	7,200 ft	17,000 ft	29,300 ft	44,000 ft
2.4°	5,800 ft	12,300 ft	27,200 ft	44,500 ft	64,400 ft
3.1°	7,500 ft	15,600 ft	33,600 ft	54,200 ft	77,400 ft
Width	2,200 ft	4,400 ft	8,800 ft	13,100 ft	17,500 ft

How to read the pictures

Reflectivity: How strongly rain, snow and hail send the pulse back, in dBZ: the stronger, the heavier.
Velocity: The wind along the beam, in mph: green toward the radar, red away. Where the two meet tightly, the wind turns.
Storm relative velocity: The same wind with the storms’ own motion taken away, so a storm’s turning stands out: a tight pair of green and red is a rotating storm.
Correlation coefficient: How alike the returns of one pulse are, 0 to 1: rain and snow near 1, hail and melting snow lower, and debris a tornado lifts well below 0.8.
Differential reflectivity: How much wider than tall what falls is, in dB: large flat raindrops read high, hail and dry snow near 0.

Each picture is one tilt of one scan, as the radar sent it: its lowest tilt first, then three above it, the angles its scan pattern sets. A picture at a higher tilt sees higher into a storm, and farther over the ground at each distance. Press a point on the map to read the value there.

As data: /radar/now.json?show=sref&site=KTLH, the times of its frames, and /radar/s/KTLH/storms.json, the storms it tracks.